The prior art includes nozzle assemblies that require withdrawal of the individual nozzle assemblies from the windboxes before maintenance for worn portions can be performed. More specifically, the prior art structures have movable portions that are carried on pivot pins that are inserted in the sides of the generally cylindrical assembly. The generally cylindrical assembly is inserted in the windbox where the walls thereof are disposed in closely spaced relation to the outboard extremity of the pins and prevent the withdrawal of the pins. The disadvantage of such structures is that the nozzle assembly must be completely withdrawn from the windbox so that the pins may be removed and the worn parts replaced.